ABC News(WASHINGTON) — The No. 2 Senate Republican said it would be a “mistake” for the Trump administration to fire special counsel Robert Mueller.

ABC News Chief Anchor George Stephanopoulos asked Sen. John Cornyn of Texas on This Week Sunday about reports that allies of President Donald Trump are laying the groundwork for the firing of Mueller, who is investigating alleged Russian interference in the 2016 U.S. presidential election and possible collusion with Trump associates.

Cornyn responded, “I read that the president’s own lawyer says that’s not going to happen. I think that would be a mistake, myself.”

The Texas senator added that Mueller should make sure that FBI agents and prosecutors on his team are completely unbiased. A senior FBI agent was removed from Mueller’s team after repeatedly calling Trump an “idiot” in text messages.

“There are plenty of FBI agents and prosecutors who have not been politically involved on behalf of Democrats or overtly critical who can serve in this important investigation,” Cornyn said. “I have confidence in Director Mueller. I just think that he would be concerned about the appearance of conflicts of interest that would undermine the integrity of the investigation.”

Cornyn also said he’s “confident” the Republican tax plan will pass this week, saying it will benefit the economy and individual Americans.

“We’re going to get the economy roaring back again, and improve pay, and increase jobs, and make America more competitive in the global economy, as well as simplifying the tax code and giving everybody in every tax bracket a tax cut,” Cornyn said. “I am confident we will pass this, probably on Tuesday.”

Stephanopoulos asked if Republicans would still be able to pass the tax legislation if Sen. John McCain of Arizona, who is currently in a hospital as he battles cancer, does not return to Capitol Hill by Tuesday.